• Title/Summary/Keyword: penetration energy

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Rod effects on transferred energy into SPT sampler using smart measurement system

  • Park, Geunwoo;Kim, Namsun;Hong, Won-Taek;Lee, Jong-Sub
    • Smart Structures and Systems
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    • v.30 no.2
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    • pp.159-172
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    • 2022
  • To improve the accuracy of the standard penetration test (SPT) results, smart measurement system, which considers the energy transfer ratio into the sampler (ETRSampler), is required. The objective of this study is to evaluate the effects of joints and rod length on the transferred energy into the sampler. The energy transfer ratios into the rod head (ETRHead) and ETRSampler, and the energy ratio from the head to the sampler (ERHS) were obtained using energy modules, which were installed at the rod head and above the SPT sampler. Linear regression analyses are conducted to correlate the ERHS with the number of joints, rod length, and SPT N-values. In addition, the dynamic resistances are calculated using both transferred energies into the rod head and into the sampler, and are compared with the corrected cone tip resistance measured from the cone penetration test (CPT). While the ETRHead are generally constant, but the ETRSampler and ERHS gradually decrease along the depth or the number of joints, except at certain depths with high SPT N-values. Thus, the ERHS can be estimated using the number of joints, rod length, and SPT N-values. The dynamic resistance evaluated by ESampler produces a better correlation with the corrected cone tip resistance than that by EHead. This study suggests that transferred energy into the SPT sampler may be effectively used for more accurate subsurface characterization.

Linear Temperature Dependence of Magnetic Penetration Depth Length at Low T in an Isotropic Superconductor

  • Nam, Sang-Boo
    • Progress in Superconductivity
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    • v.2 no.1
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    • pp.11-14
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    • 2000
  • The notion of the finite pairing interaction energy range Td is shown to result in a linear temperature dependence of the London magnetic penetration depth length, ${\Delta}{\lambda}{/\lambda}(0)=(T/Td)2/\pi)ln2$ at low T in the case of the s-wave pairing state, accounting for data of high Tc superconductor by Hardy et al.

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A Study on Optimal Hybrid-Renewable Energy Configuration of Islanded Microgrids (독립형 마이크로그리드에서 신재생에너지 최적구성 알고리즘에 관한 연구)

  • Woo, Sang-Min;Lee, Sung-Hun;Kwag, Hyung-Gun;Kim, Sung-Yul;Son, Hyun-Il;Kim, Jin-O
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.511-515
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    • 2012
  • At the moment, with an interest in renewable energy sources (RES) that continue to grow its penetration will be expected to considerably increase in the future power system. However, this penetration of RES leads to new challenges to be solved in electric power systems. In this paper, optimal configuration of renewable energy resources and operation strategy is presented. By using this methodology for allocation of the optimal sizes and types, system operational efficiency and stability of the microgrid will be maximized.

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Physical Charateristics of Elastomer Modified Asphalt (탄성체로 개질된 아스팔트의 물리적 특성)

  • Lee, S.J.;Lee, S.J.;Lee, J.K.
    • Elastomers and Composites
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    • v.32 no.3
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    • pp.166-172
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    • 1997
  • The objective in this study was investigated temperature susceptibility and low temperature fracture of rubber modified asphalt. A chlorinated polyethylene elastomer, Tyrin CM0730, was added to 200/300 grade asphalt with 3.0 and 5.0wt% to improve campatibility. The elastomer modified asphalts were analyzed for temperature susceptibility relating to penetration index(PI) and penetration-viscosity number(PVN) as well as low temperature fracture relating to fracture energy $(G_{IC})$. These indices were obtained from the measurements of penetration, viscosity, failure load and modulus. The addition of small amounts of elastomer to the asphalt resulted in a significant increase of both the PI and PVN over an unmodified asphalt. Also, the fracture energy increased with the addition of elastomer to asphalt. These significant improvement at both the high and low temperature result in enhanced performance.

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Risk Analysis of Thaw Penetration Due to Global Climate Change in Cold Regions

  • Bae, Yoon-Shin
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.2
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    • pp.45-51
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    • 2009
  • A probabilistic approach may be adopted to predict freeze and thaw depths to account for the variability of (1) material properties, and (2) contemporary and future surface energy input parameters(e.g. air temperatures, cloud cover, snow cover) predicted with global climate models. To illustrate the probabilistic approach, an example of the predicted of thaw depths in cold regions is considered. More specifically, the Stefan equation is used together with the Monte Carlo simulation technique to make a probabilistic prediction of thaw penetration. The simulation results indicate that the variability in material properties, surface energy input parameters and temperature data can lead to significant uncertainty in predicting thaw penetration.

An Analysis of Ice Impact Force Characteristics for the Arctic Structure Shape (극지 구조물 형상에 대한 빙충격 하중 특성 분석)

  • Jeong, Seong-Yeob;Cho, Seong-Rak
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.6
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    • pp.469-477
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    • 2012
  • This paper describes the characteristic analysis of ice impact force for the Arctic structure shape. In the present study an energy method has been used to predict the impact force during the ice-structure collision. This study also employs two concepts for reference contact area and normalized stress in analysis procedure. The influences of factors, such as impact velocity, full penetration depth, structure shape and ice floe size, are investigated. Full penetration occurs, particularly at lower impact velocity when ice thickness increase. But "typical size" ice floe does not expected ever to achieve full penetration during the impact procedure. The structure shape is the dominant factor in ice impact force characteristic. The results for various ice-structure collision scenarios are analyzed.

A Study on Laser Welding of the Seat Back Frame Applied by High Strength Steels (고장력 강판을 적용한 Seat Back Frame의 레이저용접에 관한 연구)

  • Seol, Hyeon Uk;Jung, Byung Hun;Kim, Sok Won
    • Journal of Welding and Joining
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    • v.35 no.3
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    • pp.62-67
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    • 2017
  • The automotive industry is in constant pursuit of alternative materials and processes to address the ever changing needs of their customers and the environment. Applications of laser welding have increased steadily in recent years due to its benefits including high speed, high productivity, and high energy density of heat source. This paper investigated the relationship between laser welding parameters and penetration characteristics. The Welding power was fixed at 5kW and welding speeds were varied for the thickness of the workpiece material. Full penetration occurred in the energy per unit area of $21J/mm^2$. The hardness of the weld zone was different for each strength of the workpiece material, however the lowest hardness values were the same in the heat-affected zone.

Theoretical resistance in cylindrical electrodes with conical tip

  • Hong, Chang-Ho;Kim, Jin-Seop;Chong, Song-Hun
    • Geomechanics and Engineering
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    • v.30 no.4
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    • pp.337-343
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    • 2022
  • The electrical resistivity method is a well-known geophysical method for observing underground conditions, (such as anomalies) and the properties of soil and rock (such as porosity, saturation, and pore fluid characteristics). The shape of electrodes used in an electrical resistivity survey depends on the purpose of the survey and installation conditions. Most electrodes for field applications are cylindrical for sufficient contact with the ground, while some are conically sharpened at their tips for convenient penetration. Previous study only derived theoretical equations for rod-shaped electrodes with spherical tips. In this study, the theoretical resistance for two cylindrical electrodes with conical tips is derived and verified experimentally. The influence of the penetration depth and tip on the measurement is also discussed.

Prelinimary Engagement Effect Analysis of Isotropic Kinetic Energy Warhead (등방성 운동에너지 탄두의 교전 효과 예비 분석)

  • Shim, Sang-Wook;Hong, Seong-Min;Seo, Min-Guk;Tahk, Min-Jea
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.5
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    • pp.440-448
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    • 2015
  • Kinetic energy(KE) rod warhead system is a new interceptor which combines advantages of existing ones. This system is less dependant on a precision guidance than direct hit type warhead and gives high penetration rates than blast fragmentation type warhead. In this paper, isotropic KE rod warhead system is introduced with detonation/deployment model. A penetration effects of the deployed rods are calculated using TATE penetration equation. Also, an engagement performance analysis method is suggested. Finally, an optimal detonation time and engagement geometry is derived by Monte-Carlo simulation in various engagement situation using the performance analysis factor.